Dual swing gate control system

ABSTRACT

A control system and method for ensuring proper closure of a dual swing gate. The control system employs position sensors for monitoring the position of each gate arm. A “differential position” is maintained between the arms during closing to ensure proper sequencing. The control system regulates the speed of the master arm and the slave arm to ensure that the differential position is maintained throughout the closure process.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of access control devices, such asthe type that are used to control vehicular traffic. More specifically,the present invention comprises a control system for actuating theopening and closure of dual swing gates.

2. Description of the Related Art

Dual swing gates are common devices used to control vehicular traffic.Dual swing gates are characterized by a pair of swing gates that move inunison. Typically, each gate blocks approximately half of the width ofthe access point when in the closed position. These gates are commonlyused to regulate vehicular access to residences, parking garages, andindustrial or commercial areas.

Most dual swing gates are electronically controlled so that anauthorized vehicle is permitted to pass through the gate when theauthorized vehicle approaches the gate. Various mechanisms are used toregulate the opening of the dual swing gate. Bar code scanners, cardreaders, infrared motion detectors, and currency counters are allcommonly used to send an “open gate” command to a controller. Thecontroller interfaces with a prime mover to open the gate when thissignal is received. Motion sensors or sensors embedded in the roadwayare often used to provide an “all clear” signal to the controller whenthe vehicle is clear of the dual swing gate. The controller is thenprovided with a “close gate” signal after the “all clear” signal isreceived.

Many dual swing gates employ locking or closing features which helpsecure the access point. For most locking or closing features to workproperly, the swing gates must arrive at the closed position in thecorrect sequence. FIG. 1 illustrates the correct closure of a dual swinggate. Housing 10 and housing 20 contain motors and control devices foractuating master arm 12 and slave arm 18, respectively. In thisinstance, slave arm 18 reached its closure position prior to master arm12. The correct timing allowed electronic lock device 14 to engageelectronic lock receiver 16. FIG. 2 illustrates the incorrect closure ofa dual swing gate. In this example, master arm 12 reached the closureposition prior to slave arm 18. Because the gates closed out ofsequence, electronic lock device 14 cannot engage electronic lockreceiver 16.

Conventionally, this sequencing problem has been addressed by using atime delay between the movement of one gate (the “master”) and the other(the “slave”). The time delay is controlled by the circuitry of acontrol card that electronically actuates the movement of the mastergate and the slave gate. Typically, the fixed time delay is useradjustable via DIP switch or potentiometer. A time delay ofapproximately four seconds is customary. When the “close gate” commandis initiated, the controller first actuates closure of slave arm 18.Once the designated delay time elapses, master arm 12 is actuated.Assuming that both gates are traveling at the same speed, slave arm 18should reach the closure point before master arm 12. This method isconsidered “open-loop” control.

There are many problems with this open-loop control protocol. First, thedelay time may be insufficient to ensure correct sequencing if themaster arm moves faster than the slave arm. Also, the relative speed ofthe gates may change over time due rendering the original delay timeinsufficient. The slave arm may have a smaller opening angle than themaster arm. For example the slave arm may open to 80 degrees while themaster arm opens to 100 degrees. In addition, using extended delayperiods to compensate for the potential of aging can cause some toperceive that master gate has stopped working. For example, if themaster arm is set to a 4 second delay period and the slave arm takes 2seconds to close, there will be a period of 2 seconds when neither gateis moving. These control systems are not user friendly since thesequencing of the gates must be observed periodically because of theaforementioned factors which can negatively affect proper sequencing. Asa result, may users tend to select the longest delay times that arepossible to ensure proper closure. This increases the total time ofclosure and decreases the security and effectiveness of the accesscontrol system.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a control system and method for ensuringproper closure of a dual swing gate. The control system employs positionsensors for monitoring the position of each arm. A “differentialposition” is maintained between the arms during closing to ensure propersequencing. The control system regulates the speed of both the masterarm and the slave arm to ensure that the differential position ismaintained throughout the closure process.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a top view, showing a prior art dual swing gate system that isclosed properly.

FIG. 2 is a top view, showing a prior art dual swing gate system that isclosed improperly.

FIG. 3 is a flowchart, showing the process control method.

FIG. 4 is a top view, showing a dual swing gate system opening.

FIG. 5 is a top view, showing a dual swing gate system opening.

FIG. 6 is a top view, showing a dual swing gate system in the openposition.

FIG. 7 is a top view, showing a dual swing gate system closing.

FIG. 8 is a top view, showing a dual swing gate system closing.

FIG. 9 is a top view, showing a dual swing gate system closing.

FIG. 10 is a top view, showing a dual swing gate system in the closedposition.

FIGS. 11A-11H show the schematic for the control card.

FIGS. 12A-12B show the schematic for the control card.

REFERENCE NUMERALS IN THE DRAWINGS

10 housing 12 master arm 14 electronic lock device 16 electronic lockreceiver 18 slave arm 20 housing 22 start close command 24 run slavecommand 26 comparison step 28 don't run command 30 run master command 32comparison step 34 reduce master speed command 36 comparison step 38stop/run command 40 comparison step 42 stop command 44 comparison step46 increase master command 48 linear actuator 50 linear actuator

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises a control system and method for ensuringproper closure of a dual swing gate. Although the proposed controlsystem actuates both the opening and closing processes, the closingprocess will be considered in greatest detail. The control systememploys position sensors for monitoring the position of each gate leafarm. Each arm is actuated by a motor and, in one embodiment, a linearactuator. As an arm moves from the closed position to the open position,the outboard end of the arm (the end which is in proximity to theopposing gate arm when in the closed position) defines an arc. This arctypically is in the range of 70 degrees to 120 degrees.

The position sensors track the rotation of the motor by observing themotor or the shaft of the linear actuator. Many different positionsensors capable of tracking or counting the revolutions of a motor shaftare known in the prior art. By tracking the number of rotations of eachmotor it is possible for the controller to “know” the position of eacharm along its respective arc. The present method maintains a“differential position” between the arms during the closing process toensure proper sequencing. The control system accomplishes this byregulating the speed of the master arm and the slave arm to ensure thatthe differential position is maintained throughout the closure process.

A method for controlling the closure of a dual swing gate system isillustrated in FIG. 3. A controller initiates the process when startclose command 22 is received. Start close command 22 may beautomatically transmitted after a period of time has lapsed from thetime the gate was opened or it may be transmitted by a sensor when thepassageway controlled by the dual swing gate is clear of vehicles.Alternatively, the close command may be user initiated remotely orlocally. Upon receipt of start close command 22, the controllergenerates run slave command 24. This control signal actuates the motorand linear actuator of the slave arm to operate at a preset speed.

The controller next determines whether or not the actual differentialposition (DP) between the slave position (SP) and the master position(MP) is greater than the designated differential position as indicatedby comparison step 26. The designated differential position (DP)represents the preset “lag” that is maintained between the slave arm andthe master arm during closing. The actual differential position (SP-MP)is the actual difference in position between the slave arm and themaster arm. Those that are skilled in the art will appreciate thatvalues may be assigned for discrete positions along the closing arc(from the fully open position to the fully closed position). Forexample, when in the fully opened position, the master arm positionalvalue (MP) may have the value of zero (0). When in the closed position,MP may have the value of nine thousand (9000). Likewise, when in thefully opened position, the slave arm positional value (SP) may have thevalue of zero (0). When in the closed position SP may have the value ofnine thousand (9000). The value for DP may be set to any reasonablenumber. To maintain a three (3) degree lag between the slave arm and themaster arm, DP should be set to the value of three hundred (300) in thepresent example.

If the actual differential position (SP-MP) has not exceed thedesignated differential position (DP), don't run command 28 isgenerated. Don't run command 28 triggers a time delay before comparisonstep 26 is repeated. If after the designated time has lapsed, the actualdifferential position exceeds the designated differential position, runmaster command 30 is generated. This command actuates the master armmotor to operate at a preset speed. The master arm motor is preferablyset to operate at the same speed as the slave arm motor.

After run master command 30 is transmitted, the controller determineswhether the actual differential position is less than the designateddifferential position as indicated by comparison step 32. If the actualdifferential position is less than the designated differential position,reduce master speed command 34 is generated. The controller then checksto see if the slave arm has reached the closed position (i.e., it checksto see if MP=9000) as indicated by comparison step 36. If the slave armhas not reached the closed position, the controller returns tocomparison step 32 to repeat the process. Those that are skilled in theart will recognize this as a closed loop control process.

If the controller determines that the actual differential position isnot less than the designated differential position via comparison step32, the controller determines whether the actual differential positionexceeds a designated differential position range via comparison step 44.In the present example, the differential position range is between 300and 310 (DP+10). If the actual differential position does not exceed therange, the controller repeats comparison step 36. If the actualdifferential position exceeds the designated differential positionrange, increase master command 46 is generated. Increase master command46 increases the operational speed of the master arm motor. Afterincrease master command 46 is generated, the controller returns tocomparison step 36 to determine if the slave arm has reached the closedposition.

Once the controller determines that the slave arm has reached the closedposition via comparison step 36, stop/run command 38 is generated. Thiscommand causes the slave arm motor to stop running and the master armmotor to operate at maximum speed. After stop/run command 38 isgenerated, the controller determines whether the master arm has reachedthe closed position (i.e., it checks to see if MP=9000) via comparisonstep 40. If the master arm has not reached the closed position, thecontroller waits for a designated amount of time and then repeatscomparison step 40. When controller 40 determines that the master armhas reached the closed position, stop command 40 is generated. Stopcommand 40 causes the master arm motor to stop running.

FIGS. 4-9 illustrate the sequencing of the opening and closing process.FIG. 4 illustrates the initiation of the opening process. The controllerfirst actuates the master arm motor contained in housing 10. Thisactuates linear actuator 48 and causes master arm 12 to move from theclosed position to a partially open position. Electronic locking device14 disengages from electronic locking receiver 16 during this phase.Once master arm 12 has attained a designated position, the controlleractuates the slave arm motor in housing 20.

Turning to FIG. 5, the dual gate system is shown in a later stage duringthe opening process. The slave arm motor in housing 20 has been actuatedcausing linear actuator 50 to move slave arm 18 to a partially openposition. The actual differential position represents the differencebetween the current position master arm 12 relative to the closedposition of master arm 12 and the current position of slave arm 18relative to the closed position of slave arm 18. In the present example,the differential position is much greater than the three (3) degree lagdescribed in relation to the example of FIG. 3.

FIG. 6 shows the dual swing gate system in the fully open position. Oncethe controller receives a start close command, the controller actuatesthe slave arm motor to initiate the closing process as describedpreviously. Turning to FIG. 7, the reader will note that slave arm 18has changed position while master arm 12 has remained idle. Once theactual differential position reaches the designated differentialposition, the controller actuates the master arm motor to initiate theclosing of master arm 12.

Turning to FIG. 8 and then to FIG. 9, the reader will note that a nearconstant differential position is maintained between master arm 12 andslave arm 18 during the closing process. With reference to FIG. 9, thecontroller arrests the slave arm motor when slave arm 18 reaches theclosed position as shown. The controller then actuates the master armmotor which drives linear actuator 48 to operate at maximum speed. Itshould be noted that a “soft close” feature could be added to slow themovement of master arm 12 immediately before it reaches the closedposition shown in FIG. 10 thus minimizing the impact of the collisionbetween electronic locking device 14 and electronic lock receiver 16.

FIGS. 11A-J and 12A-B provide schematics for the design of a controlcard capable of implementing the aforementioned control process.

The preceding description contains significant detail regarding thenovel aspects of the present invention. It should not be construed,however, as limiting the scope of the invention but rather as providingillustrations of the preferred embodiments of the invention. As anexample, many different actuation mechanisms other than linear actuatorsmay be used to open and close master arm 12 and slave arm 18. Thus, thescope of the invention should be fixed by the following claims, ratherthan by the examples given.

1. A control system for a dual swing gate, said dual swing gate having amaster arm, a slave arm, a first linear actuator for actuating saidmaster arm, a second linear actuator for actuating said slave arm, afirst motor operatively attached to said first linear actuator so thatsaid first motor drives said first linear actuator, a second motoroperatively attached to said second linear actuator so that said secondmotor drives said linear actuator, said master arm and said slave armeach configured to pivot between an open position and a closed positionwhen actuated by said first linear actuator and said second linearactuator, said control system comprising: a. a first position sensorconfigured to observe the position of said master arm; b. a secondposition sensor configured to observe the position of said slave arm; c.a controller configured to actuate said first linear actuator and saidsecond linear actuator during a closure process, said controller furtherconfigured to receive position data from said first position sensor andsaid second position sensor, wherein said controller is configured todetermine the differential position of said master arm and said slavearm during said closure process and maintain a designated differentialposition between said master arm and said slave arm during said closureprocess so that said slave arm reaches said closed position before saidmaster arm.
 2. The control system of claim 1, wherein said firstposition sensor observes said position of said master arm by sensing therevolutions of said first motor and wherein said second position sensorobserves said position of said slave arm by sensing the revolutions ofsaid second motor.
 3. The control system of claim 1, wherein saidcontroller maintains a differential position during the closure processby controlling the relative speed of said first motor and said secondmotor.
 4. The control system of claim 1, wherein said controller employsa closed control loop process to maintain said differential position,wherein during said closed control loop process said controllerdetermines whether said differential position is within a defined range.5. The control system of claim 4, wherein if when employing said closedcontrol loop process said controller determines said differentialposition is not within said defined range, said controller causes saidsecond motor to operate faster than said first motor.
 6. The controlsystem of claim 1, wherein when initiating said closure process, saidcontroller actuates said second linear actuator before actuating saidfirst linear actuator, and said controller actuates said first linearactuator only after a designated time has lapsed from the time saidsecond linear actuator was actuated.
 7. The control system of claim 1,said controller further configured to control an opening process,wherein during said opening process said controller actuates said firstlinear actuator before actuating said second linear actuator.
 8. Amethod for controlling the closure of a dual swing gate, said dual swinggate having a master arm, a slave arm, a first linear actuator foractuating said master arm, a second linear actuator for actuating saidslave arm, a first motor operatively attached to said first linearactuator so that said first motor drives said first linear actuator, asecond motor operatively attached to said second linear actuator so thatsaid second motor drives said linear actuator, said master arm and saidslave arm each configured to pivot between an open position and a closedposition when actuated by said first linear actuator and said secondlinear actuator, said method comprising: a. sensing the current positionof said master arm; b. sensing the current position of said slave arm;c. determining the differential position between said master arm andsaid slave arm, said differential position representing the differencebetween the current position of said master arm relative to said closedposition of said master arm and the current position of said slave armrelative to said closed position of said slave arm; d. comparing thedetermined differential position with a designated differential positionrange; and e. adjusting the speed of one of said first motor and saidsecond motor if said determined differential position is outside saiddesignated differential position range.
 9. The method of claim 8,further comprising the step of providing a first position sensorconfigured to sense the position of said master arm and a secondposition sensor configured to sense the position of said slave arm. 10.The method of claim 9, wherein said first position sensor observes saidposition of said master arm by sensing the revolutions of said firstmotor and wherein said second position sensor observes said position ofsaid slave arm by sensing the revolutions of said second motor.
 11. Themethod of claim 8, further comprising the step of providing acontroller, wherein said controller employs a closed control loopprocess to maintain said differential position, wherein during saidclosed control loop process said controller determines whether saiddifferential position is within said designated differential range. 12.The method of claim 11, wherein when initiating said closure process,said controller actuates said second linear actuator before actuatingsaid first linear actuator, and said controller actuates said firstlinear actuator only after a designated time has lapsed from the timesaid second linear actuator was actuated.
 13. A control system forcontrolling the opening and closing of a gate system, said gate systemhaving a slave gate element and a master gate element, wherein each ofsaid gate elements is rotatable about an axis located at a pinned end ofeach of said gate elements and whereby rotation of said gate elementsabout said axes causes a free end of each gate element to define an arcof rotation, said control system comprising: a. a first sensor, saidfirst sensor capable of determining a position of said slave gateelement along said slave gate element's arc of rotation; b. a secondsensor, said second sensor capable of determining a position of saidmaster gate element along said master gate element's arc of rotation; c.a controller in communication with said sensors and capable of comparingsaid slave gate element's position along said slave gate element's arcof rotation with said master gate element's position along said mastergate element's arc of rotation to determine a differential positionbetween said gate elements, said controller further capable of adjustinga rate of rotation of said slave gate element and a rate of rotation ofsaid master gate element such that a preselected differential positionbetween said gate elements is maintained.